As you observed and I agree, that as a (former) customer, I am free to judge them. And in fact I have. It seems you and I have judged them differently.
Same conclusion, different reasoning. The NFL is spineless in a way to antagonize pretty much everyone. It's poop in the refrigerator and eat a wheel of cheese territory. It's almost impressive. They couldn't fuck up this much on purpose.
I am not offended by their political opinions and I do not need a safe space to protect me from political opinions I do not like. Just don't do it while I'm paying you to play football. That is my objection.
They aren't doing it while playing football. If they were allowed to just play football this thread would not exist.
Other than that, I agree that there is a time and place for everything. I don't want to hear people's shit either, really. I'm a golfer. I like to watch it here or there, and I sure as fuck am likely to change the channel if I were to be exposed to the average golfer's political opinions. It just doesn't come up, so maybe I'm not really seeing this from the other side.
However, the golfers aren't being required to pay lip service to my idea of what it means to be an American. Like if they were forced to listen to a reading of MLK's Letter from a Birmingham Jail or something and decided to blow spit bubbles as a protest because they think socialism killed 100 million people. I'd be annoyed and would go out of my way to not patronize those player's sponsors, but I'd think cutting the speech would be the way to go, not forcing a respectful reaction to it. On the other hand for good or ill the anthem and ceremonial displays of patriotism, not reverence for MLK's more radical words, is the social norm, and respect for social norms carries some value.
Anyway, that being said...
Forcing people to stand for the anthem makes standing for the anthem meaningless. When person A is forced to stand, it strips person B's standing of meaning. Respect by definition is voluntary. There are those that mistake obedience for respect. That never ends well. I could draw a direct analogy to how it is a social norm to at least give lip service to respecting MLK and how that resulted in MLK's message being sanitized and distorted into lukewarm "lets just all get along" liberalism that the very same white moderates MLK railed against use to avoid confronting their collaboration in a racist society. Which is a whole different story but you get the general idea.
In a labor dispute, as you call this (and I do not agree that is all it is), there are mature ways to negotiate as opposed to, say, crybaby ways to negotiate. Intentionally and publicly violating the terms of their contract as a way to negotiate better terms is not always the most mature way to do it.
There is nothing about the anthem in the CBA.
So yes, I agree that violating the collective bargaining agreement as a way to negotiate is crybaby behavior. If the owners are wrongfully blackballing players they should suffer consequences.
Thank you for not overreacting to my occasional glib cheap shot, like the one directly above....